Purdue Professor Flags 267 Students for AI Cheating in CS 240
CS240 AI Cheating Retrospective
Dr. Jeffrey Turkstra, a teaching professor at Purdue, reflects on the Spring 2026 CS 240 course, where 267 of 584 students were flagged for AI/LLM cheating. He defends the clear syllabus policy, explains the static analysis tool Argus, and admits his response could have been better, resulting in minimal consequences for violators.
I am writing this post largely due to the number of students that continue to approach me and mention how much misinformation and inaccuracy surrounds the, apparently, ongoing discussions regarding the incident.
- aenigmaclamo
* Do not use variable length array in this class
* Some of are you are copying code and concepts from things outside of course material
* `fgetc()`, `sizeof()`, `malloc()`, etc
* You're probably cheating.
* You're also making your life more difficult
I always found these sorts of instructions quite frustrating as a student. If I'm a student enthusiastic about learning a language, I would have definitely been one of the kids trying to figure out how to use malloc and creating novel approaches to the projects that are assigned to me. It's a university class, why the hell not? Besides, isn't that going to be an advantage towards me considering the code is going to be evaluated by a anti cheat engine?
The AI stuff aside, this comes across as a professor who feels threatened when his course isn't taken as doctrine. Being called a cheater for using external resources is ridiculous to me.
- personjerry
Like other comments, I can't help feel uncomfortable with the way everything was written defensively, where every example is used to justify the author's actions.
The author concludes near the end:
> That said, I have no judgment to pass on you here.
And follows with this as the very next sentence:
> We are all human beings, we all make poor choices and mistakes in our lives.
Which seems to be clearly judging the students for their "poor choices and mistakes".
I feel the author is out of touch with the students and the times; If so many of them are leveraging AI perhaps the better move is to find ways to align that usage with learning. He quotes:
> "it is better 100 guilty Persons should escape than that one innocent Person should suffer"
But if there is such a scenario in a classroom rather than a courtroom, then perhaps the methodologies should be revisited?
It feels like the author is the ACKCHYUALLY meme, striving to prove themselves technically right, rather than empathizing with the students, which I feel shows a lack of maturity for an educator more than 2 decades older than his students.
I understand that education and evaluation is difficult in this AI era, but I can't come to agree with the author's actions or conclusions in this case.
- 2001zhaozhao
I'm pretty convinced now that grading take-home assignments is pointless with the prevalence of AI cheating. (There's surely already "innovation" going on targeted at letting people cheat on assignments while staying undetectable.)
It's probably best going forward to grade only in-person proctored exams using paper, or offline air gapped computers in the case of programming courses.
- dbalatero
I'm surprised by the negative response towards this professor. The syllabus was extremely clear up front, and students did not respect it and decided to see what they could get away with instead. Yeah there's some weird rules to follow, but the homework seems fairly scoped to smaller problems and it's just one class out of a few dozen.
- ThrowawayR2
Anyone who is lame enough to cheat on an intro to C class is doomed anyway; the AI they cheat with will be the AI that replaces them as a worker because they didn't learn anything. Give 'em hell, Prof. Turkstra!
- RomanPushkin
Professors will be the last to admit their skill set is outdated. Those folks and academia in general aren't outcome-driven. They don't care if students will be ever able to find a job or not. They just want to educate like they got used to, and want their money. Or is it me being jealous? I had to change. Change a lot, learn a lot in last couple of years. But what about those folks who still use Borland compiler? I can imagine they're comfortable in academia, and can be in the next 10 or even 20 years - depends on how aggressive they're defending their old-world principles.
- woopwoop
> Second, while the percentage of students identified was substantial, it was still less than 50%.
No doubt the student body will learn this lesson, and in the future the number of students identified as having cheated will be near zero.
- djoldman
> This form must be completed .... Failure to complete the form will result in an unfavorable letter being sent to the Dean of Students along with further potential disciplinary action.
> Through careful analysis and manual review, we have identified what we consider to be clear and concrete indicators in one or more of your homework assignment solutions that it was partially or entirely generated by an AI/LLM tool like ChatGPT, Claude, Copilot, etc....
> You are required to submit a response to this form....Failure to respond will result in a grade of 'F' for the course.
> Honest responses that align with our analysis will result in a score of O for the identified assignment(s).
> You also have the option to meet and dispute our findings. Should you choose to do so and we determine that our original findings of AI/LLM usage stand, we will instead apply the standard course policy from the syllabus and assign a grade of F for the course.
The above letter sent to a bunch of students.
> It is an open question whether this is reflective of their actual behavior or instead something that underscores the purported, and unintentional, potentially coercive nature of the form.
Sounds like the professor discovered (or disputes the possibility of?) the concept of forced confessions.
"Honest responses that align with our analysis": did the professor consider the possibility of dishonest responses that align with the analysis?
"Should you choose to do so and we determine that our original […]